Defibrillator and demand pacer catheters and methods for using same

ABSTRACT

A defibrillator and demand pacer catheter is defined by a flexible, electrically nonconductive probe having an electrically conductive pathway longitudinally disposed therein. Attached to one end of the probe is a defibrillator electrode capable of anchoring the probe to the septum of a heart and of transmitting from said conductive pathway directly to the interior of the septum a portion of an electrical defibrillation pulse sufficient to defibrillate the heart. The defibrillation pulse is delivered in such a manner so as to avoid injuring the heart tissue immediately adjacent to the defibrillator electrode. In the preferred embodiment, the defibrillator electrode is helical; however, it is also envisioned as being a lance. Alternatively, the catheter further comprises a ground electrode, a demand pacer electrode, and a supplemental defibrillator electrode attached to the probe.

RELATED APPLICATIONS

This patent application is a continuation-in-part of U.S. patentapplication Ser. No. 07/683,450, filed Apr. 10, 1991, now abandoned, inthe name of Leo Rubin and entitled "Defibrillator and Demand PacerCatheter and Method For Implantation."

BACKGROUND

1. Field of the Invention

The present invention relates to systems for regulating the contractionof a heart and more particularly to defibrillator and demand pacercatheters.

2. Background Art

The heart is a large hollow muscle used to pump blood to all parts ofthe body. Veins bring blood to the heart while arteries carry blood awayfrom the heart. Valves control the flow of blood through the heart. Thefunction of blood is to carry oxygen to the body parts. If the heartstops, the oxygen is no longer delivered and the body dies.

A muscle wall known as the septum divides the heart lengthwise into aright side and a left side. Each side has two chambers, one above theother. The upper chamber on the right side is the right atrium. Theright atrium collects blood from the body through the veins. When theright atrium is full, a valve known as the tricuspid valve opens,providing a passage to the lower chamber. The muscle tissue surroundingthe right atrium then contracts, pushing the blood into the lowerchamber.

The lower chamber is called the right ventricle. Once the tricuspidvalve closes, the muscle tissue surrounding the right ventriclecontracts, pushing the blood to the lungs. The lungs provide oxygen thatis absorbed into the blood. The blood then flows to the left side of theheart where it passes through a left atrium and a left ventricle,finally being ejected from the left ventricle to circulate through thebody.

The heart has a special system of muscles that cause the heart tissue toregularly and continuously contract. One part of the system called theS-A node regularly emits electrical signals or pulses that travelthrough the heart tissue to a second point in the heart called the A-Vnode. The heart tissue contracts in response to the electrical pulses. Asecond part of the system called the bundle of His regulates theelectrical pulses. The bundle of His insures that all muscle tissuesurrounding a specific compartment simultaneously contracts and that theatriums and ventricles contract at the appropriate time. One completecontraction of both the ventricles and the atriums constitutes a beat.

On occasion, the electrical pulses being carried through the hearttissue become irregular, causing the heart to beat rapidly or unevenly.Defibrillation is a process used to restore normal beating to a heart inthis condition. To defibrillate a heart, a large electrical chargecalled an electrical defibrillation pulse is applied directly to theheart. This electrical defibrillation pulse works to depolarize theelectrical pulses of the heart and, thereby, restore normal beating.

There are other occasions in which the heart fails to deliver a specificelectrical pulse, thereby causing the heart to pause, skipping a beat.Demand pacing is a process used to maintain normal beating of a heart inthis condition. To demand pace a heart, sensors are used to determine ifthe heart is delivering its electrical pulses at the appropriate time.If the heart is not, a relatively small electrical charge called anelectrical demand pacing pulse is applied directly to the heart toassist in electrical depolarization of the heart tissue. Individualshaving heart problems often suffer from both of the above conditionsand, thus, are benefited if they can receive both defibrillation anddemand pacer pulses.

The electrical pulses for defibrillation and demand pacing are typicallydelivered to the heart through different methods. The defibrillationpulse has historically been delivered through a large area electricalpatch sewn to the exterior surface of the heart. The electrical patch isconnected to a capacitor that is charged by a battery, thereby to becapable of delivering an electrical defibrillation pulse. Once thecapacitor discharges the defibrillation pulse, it enters directly intothe heart of the patient so as to defibrillate the heart. The pulse thenexits the body through a ground electrode attached to the skin of thepatient.

Attaching the electrical patch to the heart of the patient requires anextensive operation in which the rib cage is separated so as to exposethe heart. Once the heart is exposed, the patch can be sewn to theexterior surface. The surface area of the electrical patch must be of asufficient size to deliver the high energy defibrillation pulse withoutburning the tissue of the heart. A typical electrical patch has asurface area in the range of about 50 cm² to about 100 cm², and iscapable of delivering a defibrillation pulse with an energy of up toabout 50 joules.

In contrast, the demand pacing pulses are often applied to the heart bya demand pacer catheter. The demand pacer catheter is a long flexibleprobe, usually made of stilastic or polyurethane, with electrical leadsrunning the length of the catheter at the middle thereof. At one end ofthe probe, the leads are connected to an exposed metal surface called ademand pacer electrode. Part way up the probe, the leads are connectedto a second exposed metal surface called a ground electrode. Finally, atthe other end of the probe, the leads are connected to a regulator thathas a controller for sensing the beat of the heart and a capacitorcharged by a battery, for sending the demand pacer pulses to the heart.

The demand pacer catheter is used by making an incision in a veinleading to the heart. The end of the probe with the demand pacerelectrode is inserted into the vein and threaded to the heart and intothe right ventricle. When the heart delivers its electrical pulse to themuscle tissue, the signal is carried up the lead wires in the probe andto the controller. If the heart fails to deliver its electrical pulse,the controller senses the missing signal and tells the capacitor totransmit the electrical demand pacer pulse to the demand pacerelectrode. Once emitted from the electrode, the pulse travels throughthe blood in the right atrium and into the surrounding heart tissue,thereby causing depolarization of the heart. The pulse finally leavesthe body through the ground electrode.

In one version of the demand pacer catheter, the demand pacer electrodehas a helical or corkscrew-shaped electrode for attachment to theinterior of the heart. Such corkscrew-shaped electrodes typically have alength of about 5 mm with a surface area of about 6 mm². Furthermore,such electrodes are only capable of delivering an electrical current ofabout 5 milliamperes.

The trouble with the above-discussed approaches for applying thedifferent electrical pulses is that two procedures are required: One forinserting the demand pacer catheter and one for attaching thedefibrillator electrical patch. Furthermore, attaching the electricalpatch is an extensive operation, exposing the patient to high riskconditions and requiring a long recovery period.

Attempts have been made to solve the above problems by producing asingle catheter that can be inserted into the heart for applying bothdefibrillation and demand pacer pulses. One such catheter is animplantable, self-contained system for sensing the pulse of a heart andfor automatically sending a defibrillator or demand pacer pulse to theheart depending on the condition of the heart. An example of such acatheter is found in U.S. Pat. No. 3,857,398 issued to Leo Rubin of thepresent invention.

Similar to the demand pacer electrode previously discussed, thiscatheter has a flexible probe that can be inserted into a vein andthreaded through the right atrium and into the right ventricle of theheart. A ground electrode and a demand pacer electrode are attached tothe portion of the probe in the right ventricle. A defibrillatorelectrode is attached to the portion of the probe in the right atrium.Connected to the other end of the probe is a regulator having acontroller for sensing and analyzing the electrical pulse of the heart.The regulator further includes a defibrillator capacitor and demandpacer capacitor for transmitting their respective pulses to the heart.The capacitors are charged by a battery also located in the regulator.The regulator is inserted into the body, such as in the subcutaneoustissue of the chest wall, so that the system is independently containedwithin the body.

As the heart produces its electrical signal, the pulse is transferredthrough the probe and back to the controller. The controller then usesthis information to determine if the heart is beating properly. If not,the controller automatically informs either the demand pacer capacitoror defibrillator capacitor to transmit its respective pulse to itsrespective electrode. The pulses then travel through the blood and intothe surrounding heart tissue, thereby defibrillating or demand pacingthe heart. Finally, the charge leaves the body by the ground electrode.

One of the dilemmas associated with the above-described invention isthat it is much easier for electricity to travel through blood than itis for electricity to travel through heart tissue. As a result, amajority of the defibrillation pulse, which is delivered in the blood,travels directly to the ground electrode through the blood, rather thanentering the heart tissue. Accordingly, the heart is not defibrillated.Attempts have been made to resolve this problem by increasing the energyof the defibrillation pulse. Such an alternative, however, hasadditional drawbacks.

Blood is predominantly made of water. In turn, water molecules are madeof hydrogen and oxygen. Passing a high electrical current through waterbreaks down the water molecules to form hydrogen and oxygen gas bubbles.This is a process known as electrolysis. Studies have found thatexcessively high defibrillation pulses can result in the electrolysis ofthe blood, thereby forming hydrogen and oxygen gas bubbles within theheart. Such gas bubbles can build up enough pressure within the heart totear the heart tissue.

Furthermore, raising the strength of the defibrillation pulse increasesthe risk to the patient. If one defibrillation pulse should conductbetter than another, an excessively high defibrillation pulse couldresult in damage to the heart tissue.

Finally, increasing the size of the defibrillation pulse requires alarger capacitor to deliver the pulse which in turm increases the sizeof the regulator. Also, use of a larger capacitor requires either alarger battery to be implanted or an increase in the frequency in whichthe battery must be replaced by implanting a new regulator. Such optionsincrease the inconvenience to the patient.

Another troubling aspect is that it is difficult to target a specificcharge with the previous defibrillator and demand pacer catheters. Attimes, it may be beneficial to direct a defibrillation or demand pacerpulse to a specific point in the heart. The previous catheters arefree-floating within the heart. Therefore, they shift position with themovement of the patient or the beat of the heart. Hence, it is difficultto target the pulse.

Accordingly, some of the problems associated with the previous cathetersused to defibrillate and demand pace the heart include: multiple andcomplex operations to attach the required electrodes, the necessity touse excessively high energy pulses that result in gas bubbles andincreased threat to the patient, and the inability to strategicallytarget a pulse for optimal effect.

BRIEF SUMMARY AND OBJECTS OF THE INVENTION

Accordingly, it is an object of the present invention to provide methodsand apparatus for regulating the beating of a heart.

It is another object of the present invention is to provide a singleapparatus that can effectively deliver both defibrillator and demandpacer pulses to a heart.

Yet another object of the present invention to provide apparatus asabove that can be inserted in a single surgical procedure.

Still another object of the present invention is to provide apparatusand methods to effectively deliver a defibrillation pulse to the heartwithout causing electrolysis of the blood.

Also, another object of the present invention is to provide an apparatusthat effectively delivers a defibrillation pulse while minimizing thethreat of injury to the patient or the heart tissue.

It is yet another object of the present invention to provide anapparatus as above that can be selectively positioned in the heart totarget a defibrillator or demand pacer pulse.

Furthermore, an additional object of the present invention is tominimize the capacitor size necessary to operate the above apparatus.

Finally, it is an object of the present invention to maximize the lifespan of the battery used to operate the above apparatus so as tominimize replacement of the battery.

Additional objects and advantages of the invention will be set forth inthe description which follows, and in part will be obvious from thedescription, or may be learned by the practice of the invention. Theobjects and advantages of the invention may be realized and obtained bymeans of the instruments and combinations particularly pointed out inthe appended claims.

To achieve the foregoing objects, and in accordance with the inventionas embodied and broadly described herein, a catheter capable ofdelivering defibrillator and demand pacer pulses to the heart isprovided. The catheter comprising an elongated probe having a distal endthat can be positioned in a ventricle of the heart. Longitudinallydisposed within the probe is an electrically conducted pathway capableof delivering electrical signals, including a defibrillation pulse and ademand pacer pulse, through the probe. A defibrillator electrodeprojects from the distal end of the probe and is electrically coupledwith the electrically conductive pathway. The defibrillator electrode isstructured to deliver at least a portion of a defibrillation pulsedirectly to the interior of the septum of the heart.

Attached to the probe at a distance from the defibrillator electrode isa demand pacer electrode. The demand pacer electrode is insulated fromthe defibrillator electrode and is electrically coupled with theelectrically conducted pathway to deliver an electrical demand pacerpulse to the heart. To receive the defibrillator and demand pacer pulsesafter they are delivered to the heart, a ground electrode is attached tothe probe at a distance from the distal end. The ground electrode isalso coupled with the electrically conducted pathway.

In a preferred embodiment, the defibrillator electrode is a helix thatcan be screwed into the interior of the septum of the heart. The helixhas a length in the range of about 0.5 cm to about 1.0 cm and anelectrical surface area of at least 1.2 cm². The electrical surface areamust be sufficient to deliver an electrical defibrillation pulse of upto about 50 joules without burning the surrounding tissue.

In one embodiment, the helix is inserted into the heart tissue byrotating the entire catheter. In an alternative embodiment, the helix isindependently rotated for insertion into the septum.

It is also envisioned that the defibrillator electrode is a lance withbarbs. The lance is inserted into the heart tissue by a spring gun thatpropels the lance and embeds it into the interior of the septum. Tofacilitate insertion and removal of the lance into the septum, the barbsare structured to selectively retract into the lance.

In another embodiment, a supplemental defibrillator electrode isattached to the probe at a distance from the distal end. Thesupplemental defibrillator electrode is electrically coupled to thedefibrillator electrode and to the electrically conducted pathway suchthat the defibrillation pulse is delivered simultaneously through boththe defibrillator electrode and the supplemental defibrillatorelectrode.

The present invention also provides for a system for regulating thebeating of a heart. The system includes the catheter as previouslydiscussed attached to a regulator at the proximal end of the probe. Inthe preferred embodiment, the regulator includes a controller, adefibrillator circuit, and a demand pacer circuit. The controller sensesand analyzes the electrical charge created by the heart. Depending uponthe results of the analysis, the controller informs the demand pacercircuit or defibrillator circuit to discharge either a demand pacerpulse or a defibrillation pulse, respectively. The pulse then travelsdown the electrically conductive pathway of the catheter and isdischarged to the heart through its respective electrode.

Finally, the present invention also provides for a method for regulatingthe beating of a heart. The method includes making an incision into ablood vessel leading to the heart. The distal end of the previouslydiscussed catheter is then inserted into the blood vessel through theincision in the blood vessel. Once inserted, the catheter is threadedthrough an atrium of the heart and into a ventricle. The catheter isthen attached to the heart by anchoring the defibrillator electrode tothe septum. Preferably, this is accomplished by screwing the helicaldefibrillator electrode directly into the interior of the septum.

Electrical signals created by the heart are sensed by the controllerattached to the catheter. The controller analyses these signals, and aspreviously discussed, informs the defibrillator circuit or demand pacercircuit to transmit their respective signal. These signals are carriedthrough the probe and discharged from the respective electrodes to theheart. Finally, the pulses transmitted by the catheter leave the heartby entering the probe through the ground electrode.

BRIEF DESCRIPTION OF THE DRAWINGS

In order that the manner in which the above-recited and other advantagesand objects of the invention are obtained, a more particular descriptionof the invention briefly described above will be rendered by referenceto specific embodiments thereof which are illustrated in the appendeddrawings. Understanding that these drawings depict only typicalembodiments of the invention and are therefore not to be consideredlimiting of its scope, the invention will be described with additionalspecificity and detail through the use of the accompanying drawings inwhich:

FIG. 1 is a perspective view of the inventive defibrillator and demandpacer system implanted in the heart and chest of a patient.

FIG. 2 is an enlarged view of the distal end of the catheter shown inFIG. 1, including a first embodiment of a helical defibrillatorelectrode anchored into the muscular section of the septum.

FIG. 3 is an enlarged view of the helical defibrillator electrodeanchored into the muscular section of the septum as shown in FIG. 2,including a depiction of the tissue lining on the inner walls of theheart.

FIG. 4 is a perspective view of the inventive defibrillator and demandpacer catheter showing lead wires projecting from a probe and showing adefibrillator electrode, supplemental defibrillator electrode, demandpacer electrode and a ground electrode attached to the probe.

FIG. 5 is an enlarged view of the helical defibrillator electrodecentrally projecting from the tip of the probe, the demand pacercatheter encircling the defibrillator electrode.

FIG. 6 is a cross-sectional view of the last three turns of the helix inFIG. 5, including a depiction of the core, porous surface, andinsulation coating of the helix.

FIG. 7 is a graph of the interface resistivity between the inventivedefibrillating electrode illustrated in FIGS. 1 through 6 and the hearttissue for two types of electrode materials during long-termimplantation in non-human experimental subjects.

FIG. 8 is an electrical schematic diagram showing the defibrillationpulse traveling from the helical defibrillator electrode, through theheart tissue, into the blood and exiting the body through the groundelectrode.

FIG. 9 is an electrical schematic diagram showing the path of thedefibrillation pulse as it is simultaneously emitted from the helicaldefibrillator electrode, anchored in the septum, and the supplementaldefibrillator electrode, attached to the side of the probe.

FIG. 10 is an electrical schematic diagram showing the path of theelectrical demand pacer pulse as it is delivered from the demand pacerelectrode to the side of the septum wall.

FIG. 11 is an electrical schematic diagram showing a regulator whichincludes a controller that senses the pulse from the heart and a demandpacer circuit and defibrillator circuit which discharge electricalpulses to the heart.

FIG. 12 is a longitudinal view showing one embodiment of the catheter inFIG. 4 in which the helix is secured to the distal end of the probe.

FIG. 13 is a longitudinal view of an alternative embodiment of thecatheter in FIG. 4 in which the ground leads are partially exposed toform a ground electrode and the defibrillator leads are partiallyexposed to form a supplemental defibrillator electrode.

FIG. 14 is a longitudinal view of the tip of one embodiment of thecatheter in FIG. 4 in which the defibrillator lead is disposed withinthe probe and is connected to the helical defibrillator electrode forselective and independent rotation of the helix.

FIG. 15 is a longitudinal view of one embodiment of the tip of thecatheter in FIG. 4 in which the helix is initially contained within theprobe for easy insertion into the heart and can later be selectivelyrotated for insertion into the heart tissue.

FIG. 16 is yet another longitudinal view of one embodiment of the tip ofthe catheter in FIG. 4 in which an inner lumen is disposed within theprobe for receiving a stylet that can selectively and independentlyrotate the helical defibrillator electrode, the helix shown beingencased in water soluble material for easy insertion into the heart.

FIG. 17 is a cutaway side view of an embodiment of the catheter in FIG.4, including the defibrillator electrode being a lance that is slidablewithin the probe.

FIG. 18 is a longitudinal, enlarged view of the interior of the distalend of the lance in FIG. 17, including retractable barbs that can beexpanded to secure the lance in the interior of the septum.

FIG. 19 is a perspective view of a spring gun used to propel the lanceshown in FIG. 17 a predetermined distance into the interior of theseptum.

FIG. 20 is an exploded view of the spring gun shown in FIG. 19.

FIG. 21 is a longitudinal view of the spring gun shown in FIG. 19.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to FIG. 1, a patient 10 is shown having a chest 12 with aheart 14 made of heart tissue 15 and defined by an exterior surface 13.A vein 16 enters a right atrium 20 of heart 14 through the superior venacava 18. Right atrium 20 communicates with a right ventricle 22. Heart14 further comprises a left atrium 24 communicating with a leftventricle 26. In turn, left ventricle 26 feeds into an artery 28 whichleads away from heart 14. Right ventricle 22 and left ventricle 26 areseparated from chest 12 by an exterior right ventricle wall 23 and anexterior left ventricle wall 25, respectively. Right ventricle 22 isseparated from left ventricle 26 by a septum 30. Septum 30 has an outerwall 32 in right ventricle 22 and an outer wall 34 in left ventricle 26.The portion of septum 30 between outer walls 32 and 34 defines aninterior 36 of septum 30.

Disposed within heart 14 is a catheter 38 comprising an elongated,flexible, electrically non-conductive probe 39 having a proximal end 42and a distal end 40 that terminates in a tip 41. Electrically coupledand attached to proximal end 42 of probe 39 is a regulator 44. Catheter38 and regulator 44 comprise a system 46 that is capable of controllingthe beat of heart 14 of patient 10 by delivering electrical signals,including an electrical defibrillation pulses and an electrical demandpacer pulses, to heart 14.

Depicted in FIG. 2 is an enlarged view of distal end 40 of catheter 38disposed in heart 14. The figure shows septum 30 having a membranoussection 48 near the atriums of the heart 14 and a muscular section 50 atthe opposing end of septum 30. Muscular section 50 includes heart tissue15 located at the intersection of exterior left ventricle wall 25 andexterior right ventricle wall 23 and extends to exterior surface 13. Thewidth of septum 30 varies from about 0.7 cm to about 1.2 cm with thewidest part being at muscular section 50. Positioned near membranoussection 48 of septum 30 in interior 36 is the bundle of His 52. Bundleof His 52 functions to regulate the electrical pulses from heart 14 thattravel through heart tissue 15 to contract heart 14.

Catheter 38 is further depicted in FIG. 2 as comprising ground electrode56, exit port 58, and supplemental defibrillator electrode 72. Thesefeatures shall be discussed later in detail. In accordance with thepresent invention, however, there is also provided defibrillator meansfor anchoring probe 39 to septum 30 and for transmitting at least aportion of an electrical defibrillation pulse directly to interior 36 ofseptum 30. By way of example and not by limitation, FIG. 2 shows adefibrillator electrode 62 being a helix 64 that projects from tip 41 ofprobe 39 and terminates in a point 66. By rotating helix 64, it isadvanced into interior 36 of septum 30, thereby anchoring probe 39 toseptum 30 and enabling the delivery of a defibrillation pulse directlyto interior 36. Alternative embodiments include defibrillator electrode62 being a spike or a spear that can be inserted into septum 30.Specific alternative embodiments for the defibrillator means will bedisclosed later.

To defibrillate heart 14, a critical mass of heart tissue 15 must bedepolarized by the defibrillation pulse. It has been discovered thatheart tissue 15 located in interior 36 of septum 30 has higherelectrical conductivity than surrounding heart tissue 15. Accordingly,by delivering an electrical defibrillation pulse directly to interior36, less energy is required to defibrillate heart 14. Hence, the safetyof patient 10 is increased since the probability that electrolysis ofthe blood will occur or that heart tissue 15 will be burned isdecreased.

Optimal insertion of defibrillator electrode 62 should be within septum30 to take advantage of the highly conductive heart tissue 15 ininterior 36 but should be as far away as possible from bundle of His 52so as not to disrupt its function of regulating the heart. Ideally,defibrillator electrode 62 is inserted into muscular section 50 ofseptum 30 as shown in FIG. 3. This positioning has the additionaladvantage of using the widest portion of septum 30 which provides morearea for defibrillator electrode 62 to be inserted into. At a minimum,defibrillator electrode 62 should be inserted 5 cm from bundle of His52. How defibrillator electrode 62 is inserted in septum 30 will bediscussed later. FIG. 3 further depicts a tissue layer 68 residing inheart 14. Over a period of time, tissue layer 68 bonds to and grows oncatheter 38. In turn, this bonding effect increases the ability of thedefibrillation pulse to flow through heart tissue 15.

The embodiments shown in FIGS. 4 and 5 reveal probe 39 having an endface 70 located at tip 41 of probe 39. Attached to end face 70 is ademand pacer electrode 60 capable of delivering a demand pacer pulse andpositioned a distance from defibrillator electrode 62 so as to beinsulated therefrom. Also shown in FIG. 4 is supplemental defibrillatorelectrode 72 which is electrically coupled with defibrillator electrode62 and is capable of delivering an electrical defibrillation pulse.

Electrical signals are delivered to their respective electrodes by anelectrically conductive pathway 74 longitudinally disposed within probe39 from proximal end 42 to distal end 40. Electrically conductivepathway 74 has a first end 75 depicted in FIG. 4. Electricallyconductive pathway 74 includes ground lead 76 electrically coupled withground electrode 56, demand pacer lead 78 electrically coupled withdemand pacer electrode 60, and defibrillator lead 80 electricallycoupled with both supplemental defibrillator electrode 72 anddefibrillator electrode 62. In an alternative embodiment, defibrillatorlead 80 is electrically coupled only with defibrillator electrode 62.All leads and electrodes are insulated and separated from one another soas not to produce an electrical short. Furthermore, in the preferredembodiment all leads are made of a material having a low impedance,typically less than 10 Ohms so as to minimize energy loss. Also shown atproximal end 42 of probe 39 is atrial lumen 82 having a receiving port84. The function of atrial lumen 82 shall be discussed later.

Catheter 38 of FIG. 4 is operative in several modes. In the first mode,catheter 38 acts independently as a defibrillator. To defibrillate heart14, a defibrillation pulse is transmitted down defibrillator lead 80where it is discharged from defibrillator electrode 62 into interior 36of septum 30. A defibrillation pulse is typically in a range betweenabout 0.5 joules to about 50.0 joules. Accordingly, for defibrillatorelectrode 62 to be effective, defibrillator electrode 62 must be capableof delivering such a charge without injury to itself or the immediatesurrounding heart tissue 15.

To accomplish this, defibrillator electrode 62 is provided with anelectrical surface area 85 that is large enough to uniformly deliver theelectrical defibrillation pulse to interior 36 of septum 30 at levelslow enough not to burn heart tissue 15. Defibrillator electrode 62 hasan electrical surface area 85 in the range of about 1.2 centimeterssquared to about 2.0 centimeters squared. Such an area generallyrequires that defibrillator electrode 62 have a length in a range ofabout 0.5 centimeters to about 1.0 centimeter and that helix 64 have athickness in a range of about 7 French (cm) to about 11 French (cm).

Delivering a defibrillation pulse through helix 64 provides additionalconcerns. Helix 64 as shown in FIG. 5 has an interior surface 86 thatfaces the center of helix 64 and an exterior surface 87 that faces awayfrom the center of helix 64. Due to the shape of helix 64, as thedefibrillation pulse passes through helix 64, heart tissue 15 located inthe center of helix 64 is exposed to a much higher electrical pulse thanheart tissue 15 surrounding helix 64. Accordingly, heart tissue 15located in the center of helix 64 is easily damaged. The presentinvention however, provides an embodiment that resolves this problem.FIG. 6 depicts a cross sectional view of the last three turns of helix64 used to deliver a defibrillation pulse. Attached to interior surface86 is an insulated coating 88 which inhibits the delivery of thedefibrillation pulse to heart tissue 15 within helix 64. Accordingly,all of the defibrillation pulse is delivered through exterior surface 87of helix 64. With regard to the embodiment in FIG. 6, electrical surfacearea 85 thus constitutes exterior surface 87 of helix 64.

FIG. 6 also reveals that defibrillator electrode 60 comprises a core 90surrounded by a porous surface 92. Core 90 is made of a highlyconductive, non-corrosive metal such as titanium or platinum. Poroussurface 92 is formed by sintering finely ground metal particles,generally titanium or platinum, to core 90. To produce porous surface92, core 90 is roughened and then coated with a binder to which theparticles adhere. After the binder has dried, core 90 is sintered athigh temperatures in a reducing atmosphere to fuse the particlestogether and to the surface. The metal particles are thus joinedtogether to form an interconnecting network of pores distributeduniformly through the coating. Porous surface electrodes are describedin the Journal of Thoracic and Cardiovascular Surgery, St. Louis, Vol.78, No. 2, pp. 281-291, August 1979, C. V. Mosby Company, authored byDavid C. MacGregor, et al.

The benefit of using porous surface 92 is that electrical surface area85 of defibrillator electrode 62 is increased without substantiallyincreasing the size of defibrillator electrode 62. By increasing theelectrical surface area 85, a smaller defibrillator electrode 62 can beused to deliver the defibrillation pulse without injury to heart tissue15. A smaller defibrillator electrode 62 is preferred as it is easier toinstall and is less damaging to heart 14 when inserted in septum 30.

The use of porous surface 92 has also been found to reduce theelectrical resistance of heart tissue 15 to the defibrillation pulse.The graph in FIG. 7 shows a comparison of the effect on the resistanceof heart tissue 15 when defibrillator electrode 62 with differentsurfaces are inserted in non-human subjects over long periods of time.The study attached defibrillator electrode 62 with a porous surface 92and defibrillator electrode 62 with a titanium mesh surface to a varietyof non-human subjects. The electrical resistivity caused by heart tissue15 in response to 500 volt, 6 millisecond defibrillation pulses was thenmeasured over a twelve week period. The results are plotted on the graphin FIG. 7.

The Y-axis of the graph is the electrical resistance, measured in Ohms,caused by heart tissue 15; and the X-axis is time, measured in weeks.The solid lines are subjects using porous electrode while the dashedlines are subjects using titanium mesh electrodes. Each line has anumber designating the non-human subjects. As is evidenced by the graph,the electrical resistivity caused by the heart tissue decreases over thefirst six weeks that the defibrillator electrode 62 is inserted. This isattributed to tissue grows onto the electrodes. After six weeks, theeffectiveness of the growth by the tissue is minimized and theresistivity is generally constant.

Comparison of the porous and mesh electrodes reveals that, on average,the porous surface results in a much lower resistivity by heart tissue15. The minimum electrical resistivity using the porous electrodes aftersix weeks was 40 Ohms while the minimal electrical resistivity using thetitanium mesh electrodes after six weeks was 70 Ohms. Such a reductionin resistivity is attributed to the fact that the tissue is better ableto grow into the porous surface electrodes, thereby enhancing contactwith the tissue. Minimizing electrical resistivity in the heart tissueis beneficial since a lower charge can be used to effectivelydefibrillate heart 14.

After the electrical defibrillation pulse is delivered fromdefibrillator electrode 62 into interior 36 of septum 30, it travelsthrough heart 14, leaving the body through ground electrode 56, therebyforming a complete circuit. Ground electrode 56 is shown in FIG. 4 asattached to probe 39 at a distance from tip 41. Typically, groundelectrode 56 is positioned so as to reside in superior vena cava 18 whendefibrillator electrode 62 is anchored into septum 30. This positionrequires the defibrillation pulse to travel the length of the heart 14before it is able to exit the body, thereby maximizing the effect of thedefibrillation pulse. In alternative embodiments, ground electrode 56can be positioned independent of catheter 38 such as on the exterior ofpatient 10.

Similar to defibrillator electrode 62, ground electrode 56 has anelectrical surface area, preferably porous, in a range of about 1.2centimeters squared to about 2.0 centimeters squared. Likewise, groundelectrode 56 is made from non-corrosive, high conductive metals,preferably titanium or platinum. In FIG. 4, ground electrode 56 is shownas comprising three ring electrodes 94 that are electrically connectedin parallel with each other, each ring having a width in a range ofabout 4 millimeters to about 8 millimeters. A plurality of ringelectrodes are preferred over a single ground electrode 56 since ringelectrodes 94 permit greater flexibility of the probe and thus greaterease in inserting into heart 14.

FIG. 8 provides a schematic electrical flow diagram for catheter 38acting as a defibrillator. Electrical defibrillator current I₁ istransmitted down defibrillator lead 80 into defibrillator electrode 62where it is discharged into interior 36 at septum 30. The currenttravels through heart tissue 15 defibrillating heart 14, and thentravels into the blood where it enters ground electrode 56 and followsground lead 76.

In an alternative embodiment for defibrillation, defibrillator lead 80is also connected to supplemental defibrillator electrode 72 forsimultaneously delivering the electrical defibrillation pulse from bothdefibrillator electrode 62 and supplemental defibrillator electrode 72.Supplemental defibrillator electrode 72 has the same structuraldescription as ground electrode 56 and is shown in FIG. 4 as a pluralityof ring electrodes positioned near tip 41 of probe 39. The benefit ofusing supplemental defibrillator electrode 72 is that since supplementaldefibrillator electrode 72 delivers its portion of the defibrillationpulse in the blood, that portion of the pulse is delivered to a largearea of heart tissue 15. Thereby, it effectively assists the portion ofthe defibrillation pulse delivered in septum 30 to defibrillate heart14.

Depicted in FIG. 9 is a schematic electrical flow diagram in whichsupplemental defibrillator electrode 72 is used in combination withdefibrillator electrode 62 to deliver the defibrillation pulse.Electrical defibrillation pulse I₁ travels down defibrillator lead 80where it splits to form pulses I₂ and I₃. Pulse I₂ is delivered throughsupplemental defibrillator electrode 72 into the blood in right atrium20. Once current I₂ is discharged, it follows two general paths. PulseI₄ travels from the blood into the surrounding heart tissue and backinto the blood where it enters ground electrode 56. In contrast, pulseI₅ travels directly through the blood to ground electrode 56 withoutentering heart tissue 15. Accordingly, I₅ does not assist indefibrillating heart 14. Pulse I₃ which is delivered through helix 64has the same path as previously discussed. That is, I₃ is dischargedfrom defibrillator electrode 62 in interior 36 of septum 30 where ittravels through surrounding heart tissue 15 and into the blood, finallyentering ground electrode 56. Once currents I₃, I₄, and I.sub. 5 enterground electrode 56, they travel back up ground lead 76.

In an alternative method of operation, catheter 38 can function as ademand pacer. In this method of operation, a demand pacer pulse isdelivered to demand pacer electrode 60. Demand pacer electrode 60 has anelectrical surface area 96 in a range between about 0.4 mm² to about10.0 mm² and is made of highly conductive, non-corrosive metals such astitanium or platinum. Electrical surface area 96 of demand pacerelectrode 60 is significantly smaller than electrical surface area 85 ofdefibrillator electrode 62. This is due to the fact that the demandpacer pulse has a much smaller current requirement, typically in a rangefrom about 0.1 milliampere to about 10.0 milliamperes, than thedefibrillation pulse which can be as high as 10,000 milliamperes.Accordingly, demand pacer electrode 60 is not capable of functioning asdefibrillator electrode 62 since the delivery of a defibrillation pulsethrough demand pacer electrode 60 would most likely destroy theelectrode and burn the surrounding heart tissue 15.

In the preferred embodiment as shown in FIG. 5, demand pacer electrode60 is positioned on end face 70 such that when defibrillator electrode62 is anchored into septum 30 demand pacer electrode 60 is placedagainst outer wall 32 of septum 30. In such a position, the demand pacerpulse delivered from demand pacer electrode 62 is more efficient sincemore of the pulse is delivered directly into heart tissue 15.

Often, demand pacing is initiated immediately after defibrillation ofheart 14. Studies have found, however, that tissue immediately adjacentto a defibrillator electrode requires a time period after receiving thedefibrillation pulse before the tissue can effectively react to a demandpacer pulse. Accordingly, to permit demand pacing immediately followingdelivery of the defibrillation pulse, the demand pacer electrode 60should be placed at least 3 millimeters away from the defibrillatorelectrode 62.

In an alternative embodiment, demand pacer electrode 60 can bepositioned on probe 39 similar to supplemental defibrillator electrode72. In such an embodiment, however, the demand pacer pulse is lessefficient since it is required to first travel through the blood beforeentering the heart tissue. Accordingly, a larger percentage of the pulsetravels directly to ground electrode 56 without ever entering the hearttissue 15.

FIG. 10 is a schematic electrical flow diagram in which the demand pacerpulse is delivered through the demand pacer electrode 60 positioned onend face 70. In the flow diagram, demand pacer pulse I₆ travels downdemand pacer lead 78 where it is discharged from demand pacer electrode60 positioned against outer wall 32 of septum 30. Once I₆ is discharged,it travels in two paths. Pulse I₇, which is a majority of pulse I₆,travels directly into septum 30 and surrounding heart tissue 15. PulseI₇ then travels into the blood and finally enters ground electrode 56.Pulse I₈, which is the remainder of pulse I₆, travels directly fromdemand pacer electrode 60 through the blood and into ground electrode56. Once pulses I₇ and I₈ enter ground electrode 56, they travel upground lead 76.

In accordance with the present invention, there is also providedgoverning means for sensing and analyzing the pulse of heart 14 and foremitting an electrical defibrillation pulse or an electrical demandpacer pulse depending on the results of the analyzing. By way of exampleand not limitation, there is shown in FIG. 11 regulator 44. Regulator 44is electrically coupled with first end 75 of electrically conductivepathway 74. Regulator 44 comprises a controller 98, a demand pacercircuit 100, and a defibrillator circuit 102. FIG. 7 is a schematicelectrical flow diagram of how regulator 44 functions with catheter 38.

As the heart produces its electrical signal, controller 98 senses anelectrical potential either across ground lead 76 and demand pacer lead78 or across ground lead 76 and defibrillator lead 80. In turn,controller 98 analyzes the electrical potential or the absence of suchelectrical potential and sends a signal to either demand pacer circuit100 or defibrillator circuit 102 depending on the analysis.

When demand pacer circuit 100 receives a signal from controller 98, acapacitor within demand pacer circuit 100 transmits a demand pacer pulseto demand pacer lead 78 which travels to demand pacer electrode 60 aspreviously discussed. If defibrillator circuit 102 receives the signalfrom controller 98, a capacitor within defibrillator circuit 102transmits a defibrillation pulse to defibrillator lead 80 which travelsto defibrillator electrode 62 as previously discussed. The capacitorsreceive their energy from a power source located in controller 98. In analternative embodiment, controller 98 can receive signals from sensorsthat are independent from catheter 38. For example, the sensors can beattached to the exterior of patient 10. Operation of regulator 44 isdiscussed in greater detail in U.S. Pat. No. 3,857,398 issued Dec. 31,1974 to Leo Rubin and entitled "Electrical Cardiac Defibrillator" whichis incorporated herein by specific reference.

In the embodiment shown in FIG. 1, regulator 44 is self-contained withinpatient 10, such as within the subcutaneous tissue of the chest wall. Inan alternative embodiment, regulator 44 can be positioned outside of thepatient for monitoring patients that are maintained in a hospital.

Depicted in FIG. 12 is a longitudinal view of one embodiment of catheter38. Catheter 38 is shown as having a lumen 101 longitudinally disposedwithin catheter 38 and defining a channel 103. Located within channel103 is atrial lumen 82. Shown disposed within atrial lumen 82 is anatrial demand pacer lead 104 having a distal end 106. Attached to distalend 106 is an atrial demand pacer electrode 108. Atrial demand pacerelectrode 108 has the same structural and electrical parameters asdemand pacer electrode 60 but serves an independent function.

Demand pacer electrode 60 functions, predominantly, to pace rightventricle 22 of heart 14. However, there are times when it is beneficialto pace both right atrium 20 and right ventricle 22. To this end, exitport 58 is positioned on catheter 38 so as to reside in right atrium 20when defibrillator electrode 62 is anchored into septum 30. Thereby,atrial demand pacer electrode 108 can be positioned in right atrium 20for demand pacing right atrium 20 by simply being inserted in atriallumen 82.

Catheter 38, depicted in FIG. 12, shows helix 64 securely attached toend face 70. An insulation plug 109 is shown inserted betweendefibrillator electrode 62 and demand pacer electrode 60 to prevent theelectrodes from contacting and electrically shorting. To anchor helix 64in this embodiment, helix 64 is positioned against septum 30 aspreviously discussed, and the entire catheter 38 is rotated, therebyrotating helix 64 for advancement into interior 36 of septum 30.

An additional alternative embodiment for catheter 38 is shown in alongitudinal view in FIG. 13. The figure reveals a first layer 114, asecond layer 116, and a third layer 118 of lead wires 120 disposed inside wall 112 of catheter 38. Lead wires 120 are disposed in a spiralfashion so as to be disposed from proximal end 42 of probe 39 to distalend 40 of probe 39.

First layer 114 of lead wires 120 comprises ground lead 76. A firstcutaway section 122 of probe 39 exposes a section of ground leads 76,thereby forming ground electrode 56. Second layer 116 of lead wires 120comprises defibrillator lead 80. A second cutaway section 124 of probe39 exposes defibrillator lead 80, thereby forming supplementaldefibrillator electrode 72. Finally, third layer 118 of lead wires 120comprises demand pacer lead 78 that is electrically coupled with demandpacer electrode 60.

By using lead wires 120 as the various electrodes, the traditional ringelectrodes can be eliminated. Such an embodiment provides a more uniformflexibility to the probe. Furthermore, spirally disposing lead wires 120within sidewall 112 of probe 39 adds structural support to probe 39,thereby increasing control of catheter 38 for inserting into heart 14.Additional support is provided to probe 39 in the embodiment in FIG. 13by continuing helix 64 through interior 110 of probe 39. This embodimentof catheter 38 is also anchored to septum 30 by rotation of the entirecatheter 38. However, there are alternative embodiments in which helix64 is selectively and independently rotated of probe 39 for insertioninto septum 30.

In accordance with the present invention, there is also providedelectrode installation means for selective independent rotation of helix64 about the longitudinal access thereof to advance helix 64 into theinterior 36 of septum 30. By way of example and not limitation, there isshown in FIG. 14 a sleeve 126 encasing a rotation plate 128 which isfreely rotatable therein. Rotation plate 128 includes an exteriorsurface 130 from which defibrillator electrode 62 centrally projectstherefrom and an interior surface 132 electrically coupled with andanchored to defibrillator lead 80. Thereby, independent rotation ofdefibrillator lead 80, rotates rotation plate 128 which in turn rotateshelix 64 for insertion into interior 36 of septum 30.

An alternative embodiment for electrode installation means is depictedin FIG. 15. In this embodiment, helix 64 runs the length of probe 39 andis freely disposed therein. Positioned at tip 41 of probe 39 is a cap134 having a bore 136 of a substantially complementary configuration ofhelix 64. Thereby, selective independent rotation of helix 64 permitsthe advancement of helix 64 through end cap 134 and into interior 36 ofseptum 30. The advantage of the embodiment shown in FIG. 15 is thathelix 64 can remain in interior 110 while catheter 38 is being insertedinto heart 14, thereby, inhibiting point 66 of helix 64 from damagingpatient 10 as catheter 38 is being inserted.

Yet another embodiment for electrode installation means is depicted inFIG. 16. FIG. 16 reveals an inner lumen 138 longitudinally disposedwithin channel 103 of probe 39 from proximal end 42 to tip 41 of probe39, inner lumen 138 having an inner channel 140. A steering stylet 142having a first end 144 is freely disposed within inner channel 140 forselective rotation of helix 64. A benefit of inner lumen 138 is thatsteering stylet 142 can be positioned and rotated therein without theinterference of any other leads which may be disposed in lumen 101.

In the embodiment shown in FIG. 16, rotation plate 128 is again disposedin sleeve 126 at tip 41 of probe 39 so as to freely rotate therein.Encircling rotation plate 128 is conductor sleeve 146. Conductor sleeve146 is electrically coupled with defibrillator lead 80 and is structuredto electrically communicate with rotation plate 128 for transferring adefibrillation pulse. Interior surface 132 of rotation plate 128 isexposed to inner channel 140 of inner lumen 138.

In accordance with the present invention there is also providedattaching means for coupling first end 144 of steering stylet 142 andinterior surface 132 of rotation plate 128. By way of example and notlimitation, there is shown in FIG. 16 interior surface 132 having a slot148 capable of receiving first end 144 of steering stylet 142. First end144 has a shape substantially complementary to slot 148. Thereby,independent rotation of steering stylet 142, rotates rotation plate 128which in turn rotates helix 64 for insertion into septum 30.

Also depicted in FIG. 16 is a water soluble material 150 encasingdefibrillator electrode 62. Water soluble material 150 acts to preventpoint 66 of helix 64 from damaging patient 10 as catheter 38 is beinginserted into heart 14. Once catheter 38 is inserted, water solublematerial 150 dissolves, thereby permitting helix 64 to be inserted intoseptum 30 without obstruction. Water soluble material 150 can be made ofmaterials such as sugar that can be melted into a liquid for attachmentto helix 64 and can be dissolved in the blood without any detrimentaleffect to patient 10.

An alternative embodiment for the defibrillator means is shown in FIG.17. By way of example and not limitation, there is shown in FIG. 17 alance 152 having a distal end 154 and a side 156. Position on side 156are exit ports 158. Lance 152 is shown as being freely disposed in probe39. Depicted in FIG. 18 is an enlarged longitudinal view of distal end154 of lance 152. Lance 152 is shown as comprising a duct 160longitudinally disposed within lance 152. A retracting slot 164 isformed in distal end 154 of lance 152 so as to communicate with duct160. Furthermore, communicating with retracting slot 164 are exit ports158.

Disposed within duct 160 is a slidable shaft 170 having a first end 172with a slot 174 capable of receiving and locking first end 163 of thesteering stylet 162. Slidable shaft 170 has a second end 176 attached tobarbs 178 by hinges 180. Slidable shaft 170 is structured to selectivelyproject barbs 178 through exit ports 158 and to selectively retractbarbs 178 into retraction slot 164 by withdrawing and advancing,respectively, slidable shaft 170. Accordingly, once distal end 154 oflance 152 is inserted into interior 36 of septum 30, barbs 178 can beprojected for locking lance 152 into septum 30. To withdraw lance 152,barbs 178 are retracted into lance 152.

In accordance with the present invention there is also provided apropelling means for selectively applying a force to lance 152 to imbedlance 152 at a predetermined distance into interior 36 of septum 30. Byway of example and not limitation, there is shown in FIGS. 19, 20, and21 a spring gun 182. FIGS. 19-21 provide different views to spring gun182: FIG. 19 is a perspective view, FIG. 20 is an exploded view and FIG.21 is a longitudinal view.

Spring gun 182 comprises a body 184 having a first end 186, a second end188, an inner channel 190, a side slot 192, a top slot 194, a clamp 196attached about body 184 adjacent to top slot 194, and a hole 198extending through clamp 196. Structured on first end 186 of body 184 areexterior threads 197 and structured at second end 188 in inner channel190 are inner threads 199. Positioned in top slot 194 is latch 200having a passage 202, a lever 204, and a key 206. Latch 200 is insertedin top slot 194 and rotatably attached to clamp 196 by inserting pin 205through hole 198 and passage 202. Inserted in inner channel 190 ishammer pin 208 having a first end 210, a second end 212, a side opening214, a notch surface 216, and an aperture 218 at second end 212. Hammerpin 208 is positioned in body 184 such that side opening 214 of hammerpin 208 and side slot 192 of body 184 are aligned.

Positioned onto body 184 is handle 220 having arms 222, longitudinalpassage 224, bore 226, and locking pin 228. Handle 220 is positionedsuch that body 184 resides in longitudinal passage 224 with bore 226being aligned with side slot 192 of body 184 and side opening 214 ofhammer pin 208. Handle 220 and hammer pin 208 are slidably connected tobody 184 by pin 228 residing in bore 226, side slot 192, and sideopening 214.

Positioned against first end 210 of hammer pin 208 and within innerchannel 190 of body 184 is pin spring 230. Pin spring 230 has a firstend 232 and a second end 234. Positioned against first end 221 of handle220 is second end 236 of handle spring 238. Handle spring 238 also has afirst end 240. Attached to first end 186 of body 184 is adjusting knob242 having a first end 244, a second end 246, a bevel 248, and aninterior slot 250 having threads 252 therein. Adjusting knob 242 ispositioned such that first end 240 of handle spring 238 resides againstbevel 248 of adjusting knob 242 while first end 232 of pin spring 230resides in interior slot 250 of adjusting knob 242.

Attached to second end 188 of body 184 is a screw bar 254. Screw bar 254has a first end 256 and a second end 258. Screw bar 254 is attached tobody 184 by screwing first end 256 of screw bar 254 into inner channel190 of body 184. Positioned on screw bar 254 is first adjustment knob260 and second adjustment knob 262. Finally, spring gun 182 is alsodepicted as having a sheath 264 with a first end 266, a second end 268,and a screw cap 270 positioned at first end 266. Sheath 264 is attachedto screw bar 254 by screwing screw cap 270 of sheath 264 onto second end258 of screw bar 254.

FIG. 20 also shows lance 152 having a proximal end 272. To operatespring gun 182 for inserting distal end 154 of lance 152 into septum 30,proximal end 272 of lance 152 is threaded through sheath 264, screw bar254, and body 184 where proximal end 272 of lance 152 is inserted andattached to aperture 218 of hammer pin 208. Handle 220 is then pulledback towards adjusting knob 242, thereby also pulling back hammer pin208 and compressing pin spring 230 and handle spring 238. Handle 220 ispulled back until notch surface 216 of hammer pin 208 is parallel withkey 206 of latch 200 at which point lever 204 is lifted causing key 206of lever 204 to catch against notch surface 216 of hammer pin 208.Handle 220 can now be pressed towards latch 200 such that second end 223of handle 220 covers key 206 of latch 200, thereby forming a safety inwhich lever 204 cannot be depressed. To propel said lance, handle 220 isretracted to uncover key 206 of latch 200. Lever 204 is then depressedraising key 206 and allowing hammer pin 208 to be propelled under thepressure of pin spring 230, in turn, propelling lance 152 forward.

The distance that distal end 154 of lance 152 is projected from secondend 268 of sheath 264 is regulated by screw bar 254. The farther, screwbar 254 is inserted into second end 188 of body 184, the more lance 152projects from second end 268 of sheath 264 and; accordingly, the fartherlance 152 will be inserted into interior 36 of septum 30. The force atwhich lance 152 is propelled from sheath 264 is regulated by adjustmentknob 242. The farther adjustment knob 242 is screwed onto first end 186of body 184, the more pin spring 230 is compressed, thereby increasingthe projecting force.

Once lance 152 is inserted into septum 30, spring gun 182 can be removedfrom around lance 152. After which, probe 39 can be slid over proximalend 272 of lance 152 and pressed down to distal end 154 of lance 152,thereby producing an embodiment as shown in FIG. 17.

The method for inserting the catheter, as previously discussed, into theheart of a patient comprises the steps of:

1. making an incision into a blood vessel leading to the heart of thepatient;

2. inserting the tip of the probe into the blood vessel through theincision;

3. threading the catheter through the blood vessel of the patient to theheart thereof and then through an atrium and into a ventricle of theheart so as to be positioned against the side wall of the muscularsection of the septum; and

4. anchoring at least a portion of the defibrillator electrode directlyto the interior of the septum of the heart.

In an alternative embodiment, the catheter can be inserted into theblood vessel and threaded to the heart through an introducer which isinserted into the blood vessel. Such introducers are well known in theart. Once the defibrillator electrode is anchored, the introducer can beremoved. Anchoring the defibrillator electrode can be accomplished byrotating the entire probe so as to rotate the helix, thereby advancingthe helix into the septum; or the helix can be rotated independent ofthe probe for selective insertion into the septum. Finally, the lancecan be inserted into the septum either by simply pressing the lance intothe septum or by use of the spring gun.

When the regulator is attached to the proximal end of the probe, themethod can include the additional steps of sensing the pulse of theheart through electrically conductive pathway, analyzing in thecontroller the pulse of the heart obtained in the step of sensing, andtransmitting electrical signals from the regulator to the electricallyconductive pathway. The alternative electrical signals comprise theelectrical defibrillation pulse and the electrical demand pacer pulse.

The present invention may be embodied in other specific forms withoutdeparting from its spirit or essential characteristics. The describedembodiments are to be considered in all respects only as illustrativeand not restrictive. The scope of the invention is, therefore, indicatedby the appended claims rather than by the foregoing description. Allchanges which come within the meaning and range of equivalency of theclaims are to be embraced within their scope.

What is claimed and desired to be secured by United States patent is: 1.A method for inserting a catheter into the heart of a patient, thecatheter comprising an elongated, flexible, electrically non-conductiveprobe having a proximal end and a distal portion terminating into a tip,the heart having a right atrium communicating with a right ventricle anda left atrium communicating with a left ventricle, the left ventriclebeing separated from the right ventricle by a septum, the septum havingan outer wall in each of the left and right ventricles, the portion ofthe septum between the outer walls defining the interior of the septum,the septum also having a membranous section and a muscular section, theinterior of the septum housing the bundle of His in the membranoussection, said method comprising:(a) making an incision into a bloodvessel leading to the heart of the patient; (b) inserting the tip of theprobe into said blood vessel through said incision, the catheter furthercomprising a defibrillator electrode projecting from said tip; (c)threading the catheter through the blood vessel of the patient to theheart thereof and then through an atrium and into a ventricle of theheart so as to position said defibrillator electrode against the outerwall of the septum; and (d) anchoring said defibrillator electrodedirectly into the interior of the septum of the heart.
 2. A method asrecited in claim 1, wherein the blood vessel is a vein such that theprobe is inserted into the right atrium of the heart.
 3. A method asrecited in claim 1, wherein the step of anchoring further comprises thestep of inserting said defibrillator electrode into the interior of theseptum so that the tip of the probe is in contact with an outer wall ofthe septum.
 4. A method as recited in claim 1, wherein the step ofanchoring includes the defibrillator electrode being anchored into theseptum at a minimum distance of 5 cm from the bundle of His.
 5. A methodas recited in claim 1, wherein said portion of said defibrillatorelectrode anchored directly to the interior of the septum has anelectrical surface area in a range between about 1.2 cm² and about 2.0cm².
 6. A method as recited in claim 1, wherein the step of anchoringincludes the defibrillator electrode being anchored into the muscularsection of the septum.
 7. A method as recited in claim 1, wherein saiddefibrillator electrode comprises a helix having a longitudinal axis. 8.A method as recited in claim 7, wherein the step of anchoring includesselectively rotating said helix about said longitudinal axis independentof said probe to advance said helix into the interior of the septum. 9.A method as recited in claim 7, wherein the step of anchoring comprisesrotating said probe attached to said helix, thereby to advance saidhelix into the interior of the septum.
 10. A method for regulating thepulse of the heart of a patient through the use of a regulator and animplantable catheter, the regulator being electrically coupled with anelectrically conductive pathway longitudinally disposed within thecatheter, the catheter including an elongated, flexible, electricallynon-conductive probe having a proximal end and a distal portionterminating in a tip, the heart having a right atrium communicating witha right ventricle and a left atrium communicating with a left ventricle,the left ventricle is separated from the right ventricle by a septum,the septum having an outer wall in each of the left and rightventricles, the portion of the septum between the outer walls definingthe interior of the septum, the septum also having a membranous sectionand a muscular section, the interior of the septum housing the bundle ofHis in the membranous section, the method comprising the steps of:(a)making an incision into a blood vessel in a path leading to the heart ofthe patient; (b) inserting the tip of the probe into said blood vesselthrough said incision, said tip comprising:(i) an end face perpendicularto the probe; (ii) a helical defibrillator electrode electricallycoupled with the electrically conductive pathway and centrallyprojecting from said end face; and (iii) a demand pacer electrodeelectrically coupled with the electrically conductive pathway andpositioned on said end face at a distance from said helicaldefibrillator electrode; (c) threading the catheter through the bloodvessel of the patient to the heart thereof and then through an atriumand into a ventricle so as to position said helical defibrillatorelectrode against the outer wall, of the muscular section of the septum;(d) rotating said helical defibrillator electrode so as to advance saidhelical defibrillator electrode directly into the muscular section ofthe interior of the septum of the heart so as to contact said demandpacer electrode to the outer wall of the septum; (e) sensing the pulseof the heart through the electrically conductive pathway in the probe;(f) analyzing in the regulator the pulse of the heart obtained in saidstep of sensing; and (g) transmitting alternative electrical signalsfrom the regulator to the electrically conductive pathway depending onthe results of said step of analyzing, said alternative electricalsignals comprising:(i) an electrical defibrillation pulse transmitted tothe helical defibrillator electrode when the heart needs to bedefibrillated; and (ii) an electrical demand pacer pulse transmitted tothe demand pacer electrode when the heart needs to be paced.
 11. Amethod as recited in claim 10, wherein the blood vessel is a vein suchthat the probe is inserted into the right atrium of the heart.
 12. Amethod as recited in claim 10, wherein said helical defibrillatorelectrode has an electrical surface area in a range between about 1.2cm² and about 2.0 cm².
 13. A method as recited in claim 10, wherein saidhelical defibrillator electrode has a porous electrical surface area.14. A method as recited in claim 10, wherein the step of screwingincludes selectively rotating said helical defibrillator electrodeindependent of said probe.
 15. A method as recited in claim 10, whereinthe step of screwing comprises rotating said probe attached to saidhelix, thereby advancing said helix into the interior of the septum. 16.A method for inserting a catheter into the heart of a patient, thecatheter comprising an elongated, flexible, electrically non-conductiveprobe having a proximal end and a distal portion terminating into a tip,the heart having a right atrium communicating with a right ventricle anda left atrium communicating with a left ventricle, the left ventriclebeing separated from the right ventricle by a septum, the septum havingan outer wall in each of the left and right ventricles, the portion ofthe septum between the outer walls defining the interior of the septum,the septum also having a membranous section and a muscular section, theinterior of the septum housing the bundle of His in the membranoussection, said method comprising:(a) making an incision into a veinleading to the right atrium of the heart of the patient; (b) insertingthe tip of the probe into said vein through said incision, the catheterfurther comprising a defibrillator electrode projecting from said tip;(c) threading the catheter through said vein of the patient to the heartthereof and then through the right atrium and into the right ventricleof the heart so as to position said defibrillator electrode against theouter wall of the muscular section of the septum; and (d) anchoring saiddefibrillator electrode directly into the interior of the muscularsection of the septum of the heart.